David Woolley wrote:
>>However, as much as some will hate me for this, I'd really like to have a
>>null pseudo-class that targets css3 capable agents only, e.g. p:css3 {} ,
>
>
> Variations on this come up frequently. The problems are:
>
> - user agents are not pure CSS 2 or CSS 3 agents (this may have changed, but
> I think there are no CSS 2 agents, only ones with CSS 1 (possibly
> partial) and parts of CSS2);
> - marketing departments interpret compliance optimistically;
> - errors in conformance claims in the implementation are likely to
> have a low priority for fixing.
I think Ben Ward's !required proposal addresses these problems quite well.
http://lists.w3.org/Archives/Public/www-style/2004Dec/0084.html
It hooks into the conformance claims that user agents *already* make by parsing
and retaining the values they support.
~fantasai